Lattice instability at a fast moving crack tip

A molecular dynamics method is used to analyze the dynamic propagation of an atomistic crack tip. The simulation shows that the crack propagates at a relatively constant global velocity which is well below the Rayleigh wave velocity. However the local propagation velocity oscillates violently, and it is limited by the longitudinal wave velocity. The crack velocity oscillation is caused by a repeated process of crack tip blunting and sharpening. When the crack tip opening displacement exceeds a certain critical value, a lattice instability takes place and results in dislocation emissions from the crack tip. Based on this concept, a criterion for dislocation emission from a moving crack tip is proposed. The simulation also identifies the emitted dislocation as a source for microcrack nucleation. A simple method is used to examine this nucleation process. (C) 1996 American Institute of Physics.

Naive asymptotic expansion of the water wave generated by a slowly moving body

It is pointed out that the naive asymptotic expansion does not satisfy all the body boundary condition. A nonhomogeneous body boundary condition is obtained from this expansion. It is this condition that the additional wave term must satisfy. Moreover, because of this condition, the wave term must appear. It is pointed out that the zeroth approximation in the naive asymptotic expansion has weak singularity and the singularities become still stronger in the subsequent approximations.

KEITS Training Services: Moving to Mobile - assessment with Blackberry devices

Work-based learning provider, KEITS has improved efficiencies and institutional effectiveness with the introduction of Blackberry mobile devices to all their assessors. They have saved time and money on paper and travel, diversified evidence capture and improved their overall engagement with learners.

Moving across cultures: translation as intercultural transfer

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Crossing the Threshold, one of a series of advice and guidance publications, is designed to support use of the online e-Portfolio Implementation Toolkit and video case studies by those involved in wide-scale implementation of e-portfolios in their institutions. As the resources address the needs of both managers and practitioners, the publication has relevance for a wide range of readers in further and higher education and work-based learning. To assist the planning and effective management of a large-scale e-portfolio implementation, Crossing the Threshold follows the stages of an implementation journey with insights and guidance drawn from the toolkit and its supporting case studies. Links are provided throughout the publication to more detailed information in the two online resources.

Written words turned into moving Images: Jeanette Winterson translates "Oranges Are Not the Only Fruit for the Screen"

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EMBL-EBI: moving, sharing and controlling large datasets

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